This invention relates to radiant energy collecting devices, and in particular relates to solar energy collectors in which radiant energy is absorbed and transferred as thermal energy to a heat exchange fluid.
Various solar collector devices have heretofore been provided in the prior art for collecting and utilizing radiant energy received from the sun. Among these prior art devices are flat plate collectors in which a flat array of plates absorbs the sun's rays, with a fluid being passed in heat exchange relationship with the plates to collect and carry away thermal energy. However, such prior art devices have not achieved a high degree of efficiency in collecting the available solar energy. Temperatures of the outlet fluid have not been high, and furthermore for any given rate of energy production it has been necessary to build a collector structure having a total plate area of large dimensions with the result that costs are high in relation to the output energy rate while space utilization is low. In addition, heretofore it has been necessary to cover the entire frontal surface of flat plate collectors with a material having a good absorbtivity (.alpha.) coefficient, and this is extremely costly where it is desired to utilize a material having a very high .alpha. coefficient, such as black nickel over bright nickel, for maximum efficiency. The development of a more efficient solar collector would assist in relieving the energy shortage, would make it feasible to employ currently unused spaces for collecting such energy, such as on the spaces on the walls of a building or other structure, and would be less costly from the standpoint of materials used in making the collector.